A variety of liquid cooling systems are known. In some systems peltier units are used. Peltier units are generally more efficient than compressors in terms of energy consumption, but have a smaller cooling capacity.
US 2006/0075761 describes an apparatus for cooled or heated on demand drinking water having a thermal accumulator with embedded serpentine fluid conduit, a network of independently controlled thermoelectric heat transfer modules, and a network of temperature control modules. A preferred embodiment includes the thermal accumulator as a single die-cast thermally conductive metallic medium free of seams and an embedded pipe free of coupling structure.
WO1997007369 describes a cooling unit, suitable for a soft drinks machine or like liquid dispenser, which is compact and can cool the liquid fast enough to be acceptable in a demand-led arrangement and yet not cool it so much that it actually freezes. This application suggests the use of a cooling system that utilizes a combination of a heat pump (typically a Peltier-effect device) with an output matched to the thermal characteristics and desired throughput rate of the liquid to be dispensed coupled with—and directly cooling—an ambient medium in the form of a liquid/solid phase-change material operating in the required temperature range (which will usually be from just above 0° C. to around +5° C. This considerably reduces the possibility of over-cooling the liquid. Secondly, the application suggests a temperature-sensitive switching device, such as a thermistor thermally coupled to the liquid/solid phase-change material (15) and operatively linked to the heat pump so as to effectively control the pump on or off as required.
U.S. Pat. No. 5,634,343 describes a thermo-electric cooler capable of cooling fluid down to below 10° F. The described cooler maximizes the heat transfer path to allow better heat conductivity, and provides a space within the cooler to accommodate the thermal contraction and expansion of the cooling elements.
U.S. Pat. No. 5,285,718 describes a combination beverage brewer with cold water supply within a housing, to furnish a beverage brewing segment, at one or more locations within a housing, and a water chilling or cooling supply disposed in association therewith, to supply cold water as required. The cold water segment of the apparatus includes a cold water tank, a cooling rod therein, cooling module for operating as a heat pump for extracting warmth from the water to heat it, and delivery of the extracted heat to a heat sink, for dissipation. Various electronic and electrical controls are provided for regulating the operations of the various components of the device, and a filtering device is included for filtering the incoming water, and is coupled with various indicators for instructing when filter service is required, or the capacity of the apparatus has reached the processing of a maximum quantity of water.
US2003188540 describes a fluid cooling device for a beverage dispenser that includes: (a) a fluid accumulation vessel; and (b) a bank of thermoelectric devices provided on at least one external surface of the accumulation vessel and having cooling and heating surfaces, where the cooling surfaces are in thermal communication with the fluid accumulation vessel such that when power is supplied to the devices, the cooling surfaces decrease the thermal energy of the fluid within the accumulation vessel.
The following patents and patent applications also disclose beverage dispensers which rely, at least in part, on peltier cooling mechanisms: US 2006/096300; U.S. Pat. No. 5,501,077; U.S. Pat. No. 6,237,345; US 2006/169720; U.S. Pat. No. 5,285,718; U.S. Pat. No. 5,209,069; U.S. Pat. No. 4,664,292; US 2006/096300; U.S. Pat. No. 5,501,077 and U.S. Pat. No. 6,237,345.